Method of fixing manifold images

ABSTRACT

This invention pertains to an imaging system wherein there is employed a structure comprising a cohesively weak electrically photosensitive imaging layer sandwiched between a donor sheet and a receiver sheet. Images are produced by rendering the imaging layer cohesively weak by treatment with an activator and while subjecting the imaging layer to an electric field, it is exposed to electromagnetic radiation to which it is sensitive. With the field still applied, the sandwich is separated whereby the imaging layers fractures with the exposed portion of the imaging layer residing on one of the sheets and the unexposed portion residing on the other sheet. Images of superior quality are provided by inserting between the donor sheet and the imaging layer a solvent softenable layer which acts as a fixative for the image produced. Such images, when formed on transparent donor sheets, are particularly useful as transparencies which project a bright color image.

1 Apr. 4, 1972 METHOD OF FIXING MANIFOLD IMAGES Tulogin ..96/1 .2

Primary Examiner-Charles E. Van Horn Assistant Examiner-John C. Cooper,111 Attorney-James J. Ralabate, David C. Petre and Raymond C. Loyer [57]ABSTRACT This invention pertains to an imaging system wherein there isemployed a structure comprising a cohesively weak electricallyphotosensitive imaging layer sandwiched between a donor sheet and areceiver sheet. Images are produced by rendering the imaging layercohesively weak by treatment with an activator and while subjecting theimaging layer to an electric field, it is exposed to electromagneticradiation to which it is sensitive. With the field still applied, thesandwich is separated whereby the imaging layers fractures with theexposed portion of the imaging layer residing on one of the sheets andthe unexposed portion residing on the other sheet. Images of superiorquality are provided by inserting between the donor sheet and theimaging layer a solvent softenable layer which acts as a fixative forthe image produced. Such images, when formed on transparent donorsheets, are particularly useful as transparencies which project a brightcolor image.

1 1 Claims, 4 Drawing Figures ACTIVATE SANDWICH APPLY FIELD h AND EXPOSESEPARATE FIG. 4

FIG. 3

INVENTOR. RAY H.LUEBBE JR. BY JOHN F. BYRNE ATTORNEY METHOD OF FIXINGMANIFOLD IMAGES BACKGROUND OF THE. INVENTION The present inventionrelates in general to imaging and more specifically to a method for theformation of images by layer transfer in image configuration.

There has recently been discovered an imaging technique based on layertransfer of a material from a donor sheet to a receiver sheet under theinfluence of an applied electric field and electromagnetic radiation. Amore comprehensive discussion of imaging techniques on layer transfermay be found in copending application Ser. No. 708,380 filed Feb. 26,1968 in the US. Pat. Office.

Copending application Ser. No. 708,380 describes an imagin g systemutilizing a manifold sandwich comprising an electrically photosensitivematerial between a pair of sheets. In this imaging system, an imaginglayer is prepared by coating a layer of electrically photosensitiveimaging material onto a substrate. In one form the imaging layercomprises a photosensitive material such as metal-free phthalocyaninedispersed in a cohesively weak insulating binder. This coated substrateis called the donor. When needed, the imaging layer is renderedcohesively weak. The process step of weakening the imaging layer istermed activation and in most cases the imaging layer is activated bycontacting it with a swelling agent, solvent, or partial solvent for theimaging or by heating. After activation a receiver sheet is laid overthe surface of the imaging layer. An electrical field is then appliedacross this manifold sandwich while it is exposed to a pattern of lightand shadow representative of the image to be reproduced. Upon separationof the donor substrate or sheet and receiver sheet, the imaging layerfractures along the lines defined by the pattern of light and shadow tOwhich the imaging layer has been exposed. Part of the imaging layer istransferred to one of the sheets while the remainder is retained on theother sheet so that a positive image, that is, a duplicate of theoriginal is produced on one sheet and a negative image is produced onthe other.

After the image is formed the image is usually fixed as by fusing theimaging material onto the substrate by means of heat. Other means offixing the image have been employed such as by overcoating the imagewith a clear plastic film and then drying the film. Also images havebeen fixed by incorporating polymers in the activator which is sprayedonto the imaging material and subsequently fused. Usually the dryingstep is desirably done rapidly and thus a heating step is usuallyemployed in fixing the image. The layer transfer imaging systemdescribed above is capable of providing images on many differentsubstrates. Such substrates can be either opaque or transparent, paper,plastic coated paper, and even metal foil. In all cases the image mustbe fixed to the substrate and also provided with a durable surface sothat it will not become damaged in use. Even more difficult problemsoccur when the images are to be employed as transparencies for purposesof projection, especially by means of an overhead projector. Not only isit difficult to firmly fix the image to the clear plastic substratescommonly used in projecting images, but also the fixative must provide asmooth, clear finish in order to provide bright color in the projectedimage. Since modern projection slides are generally thin transparentsheets, the images are subjected to a greater amount of flexing thanother images. In addition, the color of many transparencies degrade uponaging due to the wear associated with use and handling. A particularproblem found with images produced by the above described layer transferprocess is the low degree of scratch resistance of the image even thoughsuch image is well fixed to the substrate. Previously images made bymeans of the layer transfer process required polishing by means of abufiing wheel because such images, as produced, have a rough, lightscattering surface.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide an imaging system overcoming the above noted disadvantages.

It is another object of this invention to provide a layer transferimaging system which provides comparatively durable images.

It is another object of this invention to provide a layer transferimaging system which provides comparatively durable images and does notrequire a separate overcoating step.

Another object of this invention is to provide a method for layertransfer imaging which produces transparencies that project high qualitybright color images.

The above object and others are accomplished in accordance with thisinvention by an imaging method utilizing a structure comprising acohesively weak electrically photosensitive imaging layer sandwichedbetween a donor sheet and a receiver sheet. In accordance with thisinvention, a donor sheet is first coated with a solvent softenable layerupon which electrically photosensitive material of the imaging layer iscoated. When the imaging layer is activated, the solvent softenablelayer is softened by the activator so as to permit mixing of thesoftenable layer with the imaging layer. The a ctivator is removed afterimaging to provide a durable, well-fixed image on the donor sheet. Byemploying transparent sheets, images can be produced which are highlysuitable for use as projection transparencies. Such superior images areobtained in accordance with this invention without including anadditional step in the actual imaging process.

In order to produce an image by means of the layer transfer processdescribed above, the imaging layer must be cohesively weak at the timethe donor sheet and receiver sheet are separated. Many electricallyphotosensitive materials must be rendered cohesively weak in order thatthe imaging layer may fracture to provide images of acceptable quality.The means normally employed to render the imaging layer cohesively weakis termed activation. Materials employed to reduce the cohesive strengthof the imaging layer are usually called an activator. Most activatorsare liquids which are applied to the imaging layer at some point duringthe imaging process. Thus, the activator may be applied either before orafter exposure to electromagnetic radiation or before or after theapplication of the electric field. In any case the need for theactivator occurs only at the time the imaging layer fractures uponseparation of the two sheets. It has now been discovered that byemploying a layer of material beneath the imaging layer which issoftened by the activator, images of superior quality are produced. Suchimages are found to be well fixed to the substrate and possess hard,clear, smooth finishes making them particularly useful as colortransparencies.

As stated above, the solvent softenable layer on the donor is affectedby the activation step in the imaging process. The activation step maytake many forms. Preferably, the activator should have a highresistivity so as to prevent electrical breakdown of the manifoldsandwich. Accordingly, it will generally be found to be desirable topurify commercial grades of activators so as to remove impurities whichmight impart a higher level of conductivity. This may be accomplished byrunning the fluid through a clay column or by employing any suitablepurification technique. Generally speaking, the activator may consist ofany suitable material having the aforementioned properties. For purposesof this specification and the appended claims, the term activator shallbe understood to include not only materials which are conventionallytermed solvents but also those which are partial solvents, swellingagents or softening agents for the imaging layer. The activator can beapplied at any point of the process prior to separation of the donor andreceiver sheets.

It is generally preferable that the activator have a relatively lowboiling point so that fixing of the resulting image can be accomplishedupon evaporation of the activator. If desired, fixing of the image canbe accomplished more quickly with mild heating at most. It is to beunderstood, however, that the invention is not limited to the use ofthese relatively volatile activators. In fact, very high boiling pointnon-volatile activators including silicone oils such asdimethyl-polysiloxanes and very high boiling point long chain aliphatichydrocarbon oils ordinarily used as transformer oils such as Wemco-Ctransformer oil, available from Westinghouse Electric Co., have alsobeen successfully utilized in "the imaging process. Although these lessvolatile activators do not dry off by evaporation, image fixing can beaccomplished contacting the final image with an absorbent sheet such aspaper which ab sorbs the activator fluid. In short, any suitablevolatile or nonvolatile activator may be employed. Typical activatorsinclude Sohio Odorless Solvent 3440, an aliphatic (kerosene) hydrocarbonfraction, available from Standard Oil Co. of Ohio, carbon tetrachloride,petroleum ether, Freon 214 (tetrafluorotetrachloropropane), otherhalogenated hydrocarbons such as perchloroethylene,trichloromonoiluoromethane, trichlorotrifluoroethane,trichlorotrifluoroethane, ethers such as diethyl ether, diisopropylether, dioxane, tetraphydrofuran, ethyleneglycol monoethyl ether,aromatic and aliphatic hydrocarbons such as benzene, toluene, xylene,hexane, cyclohexane, gasoline, mineral spirits and white mineral oil,vegetable oils such as coconut oil, babussu oil, palm oil, olive oil,castor oil, peanut oil and neatsfoot oil, decane, dodecane and mixturesthereof. Sohio Odorless Solvent 3440 is preferred because it isodorless, nontoxic and has a relatively high flash point.

The solvent softenable layer can comprise any suitable material which issoftened by the activator. Thus, a wide range of materials can beemployed depending upon the activator used in the imaging process. Forinstance, some materials are softened by aliphatic hydrocarbon fractionssuch as kerosene while others are softened by activators such ascarbontetrachloride and other halogenated hydrocarbons. Thus, the choiceof solvent softenable material to be employed in the layer is determinedby the choice of activators. Typical examples of solvent softenablematerial are thermoplastic resins such as polystyrene, polyethylene,polyisobutylene, polyepichlorohydrin, polypropylene; copolymers such asstyrene, alphamethylstyrene, vinyl toluene, n-butylmethacrylic andethylene-vinylacetate. A particularly preferred solvent softenable layeris a copolymer of vinyl toluene and styrene. Such copolymers contain amo] ratio of vinyl toluene to styrene in the range of from about 1 toabout to about 10 to l, and preferably 1 to 1.

The solvent softenable layer need not be completely soluble in theactivator employed, and it is preferred that the layer be only partiallysoluble, tackified or swelled by the activator. Thus, blends ofmaterials may be employed, some of which are soluble and some of whichare insoluble in the activator. For example, polymers and copolymers ofvarying molecular weight may be employed such that one may be moresoluble in the activator than the other. I

The solvent softenable material may be coated onto donor sheets by meansknown to the art. For example, the material may be slurried in a carrierliquid and applied by means of a doctor blade or dissolved in a solvent,coated on the substrate by means of a brush and subsequently evaporatingthe solvent. The solvent softenable layer is generally dried prior toreceiving the imaging layer. The drying process is hastened by placingthe coated substrate in an oven at a temperature in the range of fromabout 50 C. to about 100 C. for a period of from five to fifteenminutes. The imaging layer is coated on the donor sheet over the driedsolvent softenable layer.

The solvent softenable layer can be applied to the donor sheet inthicknesses ranging from about 0.5 microns to about 10 microns. The mostuseful thickness of the solvent softenable layer is in the range of fromabout 1 micron to about 3 microns.

In the manifold imaging process, the imaging layer comprises anysuitable electrically photosensitive material. Typical organic materialsinclude: quinacridones such as: 2,9- dimethyl quinacridone, 4,1l-dimethyl quinacridone, 2,10- dichloro-6, l 3-dihydro-quinacridone,2,9-dimethoxy-6l 3- dihydro-quinacridone, 2,4,9,1l-tetrachloro-quinacridone, and solid solutions of quinacridones andother compositions as described in US. Pat. No. 3,160,510; carboxamidessuch as: N-2"-pyridyl-8,l3-dioxodinaphtho-(2,l-2',3)-furan-6-carypropylamino) anthraquinone, l,5-bis (benzylamino)anthraquinone, l,5-bis (phenylamino) anthraquinone, l,2,5,6-di(c,c'-diphenyl)-thiazole-anthraquinone, 4-(2'-hydroxyphenylmethoxyamino) anthraquinone; azo compounds such as:2,4,6-tris (N-ethyl-N-hydroxy-ethyl-paminophenylazo) phloroglucinol,l,3,5,7-tetrahydroxy- 2,4,6,8-tetra(N-methyl-N-hydroxyethyl-p-amino-phenylazo) naphthalene,l,3,5-trihydroxy-2,4,6-tris (3-nitro-N-methyl-N-hydroxymethyl-4'-aminophenylazo) benzene, 3-methyl-lphenyl-4-( 3'-pyrenylazo )-2-pyrazolin-5-one, l-( 3 pyrenylazo)-2-hydroxy-3-naphthanilide, l-( 3 '-pyrenylazo )-2- naphthol, 1-( 3'-pyrenylazo )-2-hydroxypyrene, l-( 3pyrenylazo)-2-hydroxy-3-methylxanthene, 2,4,6-tris (3'- pyrenylazo)phloroglucinol, 2,4,6-tris l phenanthrenylazo)phloroglucinol,l-(2'-methoxy-5'- nitrophenylazo)-2-hydroxy-3'-nitro-3-naphthanilide;salts and lakes of compounds derived from 9-phenylxanthene, such as:phosphotongstomolybdic lake of 3,6-bis (ethylamino)-9,2'- carboxyphenylxanthenonium chloride, barium salt of 3-2'- toluidine amino-6-2''-methyl-4' -sulphophenyl-amino-9-2 carboxyphphenyl xanthene;phosphomolybdic lake of 3,6-bis(ethylamino)-2,7-dimethyl-9-2'-carbethoxy-phenylxanthenonium chloride;dioxazines such as: 2,9-dibenzoyl-6, l3-dichloro-triphenodioxazine,2,9-diacetyl-6, l3-dichlorotriphenodioxazine,3,l0-debenzoylamino-2,9-diisopropoxy- 6, l 3-dichloro-triphenodioxazine,2,9-difuroyl-6, l 3-dichlorotripheno-dioxazine; lakes of fluoresceindyes, such as: lead lake of 2,7-dinitro-4,5-dibromo fluorescein, leadlake of 2,4,5,7-tetrabromo fluoroescein, aluminum lake of 2,4,5,7-tetrabromo-l0,11,12,13-tetrachloro fluorescein; bisazo compositions suchas: N,N'-di l-(l-naphthylazo)-2-hydroxy-8- naphthyl] adipdiamide,N,N'-di-l-( l'-naphthylazo)-2-hydroxy, 8-naphthyl succindiamide, bis-4,4-(2"-hydroxy-8"-N,N'- diterephthalamidel -naphthylazo) bephenyl, 3 ,3'-methoxy- 4,4'-diphenyl-bis l"-azo-2' '-hydroxy-3 '-naphthanilidepyrenes such as: l,3,6,8-tetraaminopyrene, l-cyano-6- nitropyrcne;phthalocyanines such as: beta-form metal free phthalocyanine, copperphthalocyanine, tetrachloro phthalocyanine, the X-form of metal-freephthalocyanine as described in US. Pat. No. 3,357,989 metal salts andlakes of azo dyes; such as: calcium lake of 6-bromol (l'-sulfo-2-naphthylazo)-2-naphthol, barium salt of 6-cyano-l( l-sulfo-2-naphthylazo)-2-naphthol, calcium lake of l-(4'-ethyl-5'-chlorobenzene-2-sulfonic acid)-2-hydroxy-3-naphthoic acid; and mixturesthereof.

Typical inorganic compositions include cadmium sulfide, cadmiumsulfoselenide, zinc oxide, zinc sulfide, sulphur selenium, mercuricsulfide, lead oxide, lead sulfide, cadmium selenide, tetanium dioxide,indium trioxide and the like.

In addition to the aforementioned organic materials other organicmaterials which may be employed in the imaging layer includepolyvinylcarbazole; 2,4-bis (4,4'-diethyl-aminophenyl)- l ,3,4-oxidazole; N-isopropylcarbazole; polyvinylanthracene;triphenylpyrrol; 4,5-diphenylimidazolidinone;4,5-diphenylimidazolidinethinone; 4,5-bis-(4'-amino-phenyl)-imidazolidinone; l ,2,4,6-tetraazacyclo-octatetraene- (2,4,6,8);3,4-di-(4-methoxyphenyl)-7,8-diphenyl-l,2,5,6-tetraazocyclooctatetraene-(2,4,6,8); 3,4-di(4-phenoxy-phenyl)-7,8-diphenyl-l ,2,5,6-tetraaza-cyclooctatct1 acne-(2,4,6,8); 3 ,4,7,8-tetramethoxy-l ,2,5 ,6-tetraazo-cyclooctatetraene- (2,4 ,6,8Z-mercapto-benzthiazole; 2-phenyl-4-alphanuphthylidene-oxazolone;2-phenyl-4-diphenylidenepxazolone;2-phenyl-4-p-methoxy-benzylidene-oxazole; 6- hydroxy-2-phenyl(p-dimethyl-amino phenyl)-benzofurane; 6-

hydroxy-2,3-di (p-methoxyphenyl)-benzofurane; 2,3,5,6-tetra-(p-methoxy-phenyl)-furo-(3,2f)-benzofurane; 4-dimethyl-amino-benzylidene-benzhydrazide;4-dimethylaminobenzylideneiso-nicotinic acid hydrazide; turfurylidene,(2)-4-dimethylamino-benzhydrazide;5-benzylidene-arninoacenaphthene-3-benzylidene-amino-carbazole; (4-N,N'dimethylaminobenzylidene)-p-N,N-dimethyl aminoaniline;(Z-nitro-benzylidene)-p-bromo-aniline; N,N-dimethyl-N'-(2'nitro-4-cyano-benzylidene)-p-phenylenediamine;2,4-diphenyl-quinazoline; 2-(4T-amino-phenyD-4- phenyl-quinazoline;2-phenyl-4-(4'-di-methyl-amino-phenyl)- 7-methoxy-quinazoline;l,3-diphenyl-tetra-hydroimidazole; 1,3-di(4-chlorophenyl)-tetrahydroimidazole; l,3-diphenyl2,4-dimethylaminophenyl)-tetrahydroimidazole;l,3-di(ptolyl)-2-[quinolyl-(2-)]-tetra-hydroimidazole; 3-(4'dimethylamino-phenyl)-5-(4"-methoxy-phenyl)-6-phenyl- 1,2,4-triazine;3-pyridil-(4)-5-(4dimethylamino-phenyl)-6- phenyl-l ,2,4-triazine;3-(4-amino-phenyl)-5 ,6-di-phenyl- 1,2,4-triazine; 2,5-bis[4'-amino-phenyl-( l )-]-l,3,3-triazole; 2,5-bis[4-(N-ethyl-N-acetyl-amino)phenyl-( l 1,3,4- triazole;1,5-diphenyl-3-methyl-pyrazoline; l,3,4,5-tetraphenyl-pyrazoline;l-phenyl-3-(p-methoxy styrl)-5-(p-methoxyphenyl)-pyrazoline;l-rnethyl-2-( 3 ,4'-diphydroxymethylene-phenyl)-benzimidazole;2,(4'-dimethylamine phenyl)-benzoxazole;2-(4'-methoxyphenyl)-benzthiazole;2,5-bis[p-amino-phenyl-(1)]-l,3,4-oxidiazole; 4,5-diphenylimidazolone;3-amino-carbazole; copolymers and mixtures thereof.

Other materials include organic donor-acceptor (Lewis acid-Lewis base)charge-transfer complexes made up of aromatic donor resins such asphenolaldehyde resins, phenoxides, epoxies, polycarbonates, urethanes,styrene or the like complexed with electron acceptors such as2,4,7-trinitro-9- fluorenone; 2,4,5,7-tetranitro-9-fluorenone; picricacid; 1,3,5- trinitro benzene; chloranil; 2,5-dichloro-benzoquinone;anthraquinone-Z-carboxylic acid, 4-nitrophenyl; maleic anhydride; metalhalides of the metals and metalloids of groups 1-H and ll-Vlll of theperiodic table including for example aluminum chloride, zinc chloride,ferric chloride, magnesium chloride, caldium iodide, strontium bromide,chromic bromide, arsenic triiodide, magnesium bromide, stannous chlorideetc.; boron halides, such as boron trifluorides; ketones such asbenzophenone and anisil, mineral acids such as sulfuric acid; organiccarboxylic acids such as acetic acid and maleic acid, succinic acid,citroconic acid, sulphonoc acid, such as 4-toluene sulphonic acid andmixtures thereof. In addition to the charge transfer complexes, it is tobe noted that many other of the above materials may be furthersensitized by the charge transfer complexing technique and that many ofthese materials may be dye-sensitized to narrow, broaden or heightentheir spectral response curves.

It is also to be understood that the electrically photosensitiveparticles themselves may consist of any suitable one or more of theaforementioned electrically photosensitive materials, either organic orinorganic, dispersed in, in solid solution in, or copolymerized with,any suitable insulating resin whether or not the resin itself isphotosensitive. This particular type of particle may be particularlydesirable to facilitate dispersion of the particle, to preventundesirable reactions between the binder and the photosensitive materialor between the photosensitive and the activator and for similarpurposes. Typical resins of this type include polyethylene,polypropylene, polyamides, polymethacrylates, polyacrylates, polyvinylchlorides, polyvinyl acetates, polystyrene, polysiloxanes, chlorinatedrubbers, polyacrylonitrile, epoxies, phenolics, hydrocarbon resins andother natural resins such as resin derivatives as well as mixtures andcopolymers thereof.

The X-form phthalocyanine is preferred because of its excellentphotosensitivity although any suitable phthalocyanine may be used toprepare the imaging layer of this invention. The phthalocyanine used maybe in any suitable crystal form. It may be substituted or unsubstitutedboth in the ring and straight chain portions. Reference is made to abook entitled Phthalocyanine Compounds by F. H. Moser and A. L. Thomas,published by the Reinhold Publishing Company, 1963 edition for adetailed description of phthalocyanines and their synthesis. Anysuitable phthalocyanine may be used in the present invention.Phthalocyanines encompassed within this invention may be described ascompositions having four isoindole groups linked by four nitrogen atomsin such a manner so as to form a conjugated chain, said compositionshave the general formula (C H N R,, wherein R is selected from the groupconsisting of hydrogen, deuterium, lithium, sodium, potassium, copper,silver, beryllium, magnesium, calcium, zinc, cadmium barium, mercury,aluminum, gallium, indium, lanthanum, neodymium, samarium, europium,gadolinium, dypsprosium, holmium, erbium, thulium, ytterbium, lutecium,titanium, tin, hafnium, lead, silicon, germanium, thorium, vanadium,antimony, chromium, molybdenum, uranium, manganese, iron, cobalt,nickel, rhodium, palladium, osmium and platinum; and n is a value ofgreater than 0 and equal to or less than 2. Any other suitablephthalocyanines such as ring or aliphatically substituted metallicand/or non-metallic phthalocyanines may also be used if suitable. Asabove noted, any suitable phthalocyanine may be used to prepare thephotoconductive layer of the present invention. Typical phthalocyaninesare: aluminum phthalocyanine, aluminum polychlorophthalocyanine,antimony phthalocyanine, barium phthalocyanine, berylliumphthalocyanine, cadmium hexadecachlorophthalocyanine, cadmiumphthalocyanine, calcium phthalocyanine, cerium phthalocyanine, chromiumphthalocyanine, cobalt phthalocyanine, cobalt chlorophthalocyanine,copper 4-aminophthalocyanine, copper bromochlorophthalocyanine, copper4-chlorophthalocyanine, copper 4-nitrophthalocyanine, copperphthalocyanine, copper phthalocyanine sulfonate, copperpolychlorophthalocyanine, deuteriophthalocyanine, dysprosiumphthalocyanine, erbium phthalocyanine, europium phthalocyanine,gadolinium phthalocyanine, gallium phthalocyanine, germaniumphthalocyanine, hafnium phthalocyanine, halogen substitutedphthalocyanine, holrnium phthalocyanine, indium phthalocyanine, ironphthalocyanine, iron polyhalophthalocyanine, lanthanum phthalocyanine,lead phthalocyanine, lead polychlorophthalocyanine, cobalthexaphenylphthalocyanine, copper pentaphenylphthalocyanine, lithiumphthalocyanine, lutecium phthalocyanine, magnesium phthalocyanine,manganese phthalocyanine, mercury phthalocyanine, molybdenumphthalocyanine, anphthalocyanine, neodymium phthalocyanine, nickelphthalocyanine, nickel polyhalophthalocyanine, osmium phthalocyanine,palladium phthalocyanium, palladium chlorophthalocyanine,alkoxyphthalocyanine, alkylaminophthalocyanine,alkylmercaptophthalocyanine, aralkylaminophthalocyanine,aryloxyphthalocyanine, arylmercaptophthalocyanine, copper phthalocyaninepiperidine, cycloalkylaminophthalocyanine, dialkylarninophthalocyanine,diaralkylaminophthalocyanine, dicycloalkylaminophthalocyanine,hexadecahydrophthalocyanine, imidomethylphthalocyanine,1,2-naphthalocyanine, 2,3-naphthalocyanine octaazaphthalocyanine, sulfurphthalocyanine, tetraazaphthalocyanine,tetra-4-acetylaminophthalocyanine, tetrachloromethylphthalocyanine,tetradiazophthalocyanine, tetra-4,4-dimethyloctaazaphthalocyanine,tetra-4,5-diphenylenedioxide phthalocyanine, tetra-4,5-diphenyloctaazaphtha1ocyanine, tetra-(-methylbenzothiazoyl)phthalocyanine, tetra-p-methylphenylaminophthalocyanine,tetramethylphthalocyanine, tetranaphtho-triazolylphthalocyanine,tetra-4-naphthylphthalocyanine, tetra-4-nitrophthalocyanine,tetraperi-naphthlene-4,

S-acta-azaphthalocyanine, tetra-2,3-phenyleneoxide phthalocyanine,tetral4-phenyl-octaazaphthalocyanine, tetraphenylphthalocyanine,tetraphenylphthalocyanine tetracarboxylic acid;tetraphenylphthalocyanine tetrabarium carboxylate,tetraphenylphthalocyanine tetra-calcium carboxylate,tetraphyridylphthalocyanine, tetra-4-trifluoromethylmercaptophthalocyanine, tetra-4-trifluoromethylphthalocyanine, 4,5-trionaphtheneoctaazaphthalocyanine, platinum phthalocyanine, potassiumphthalocyanine, rhodium phthalocyanine, samarium phthalocyanine, silverphthalocyanine, silicone phthalocyanine, sodium phthalocyanine,sulfonated phthalocyanine, thorium phthalocyanine, thuliumphthalocyanine, tin chlorophthalocyanine, tin phthalocyanine, titaniumphthalocyanine uranium phthalocyanine, vanadium phthalocyanine,ytterbium phthalocyanine, zinc chlorophthalocyanine, zincphthalocyanine, others described in the Moser text and mixtures, dimers,trimers, oligomers, polymers, copolymers or mixtures thereof. The basicphysical property desired in the imaging layer is that it be frangibleas prepared or after having been suitably activated. That is, the layermust be sufficiently weak structurally so that the application ofelectrical field combined with the action of antinic radiation on theelectrically photosensitive materials will fracture the imaging layer.Further, the layer must respond to the application of field the strengthof which is below that field strength which will cause electricalbreakdown or arcing across the imaging layer. Another term forcohesively weak," therefore, would be field fracturable.

The imaging layer serves as the photoresponsive element of the system aswell as the colorant for the final image produced. Other colorants suchas dyes and pigments may be added to the imaging layer so as tointensify or modify the color of the final image produced when color isimportant. Preferably, the imaging layer is selected so as to have ahigh level of response while at the same time being intensely colored sothat a high contrast image can be formed by the high gamma system ofthis invention. The imaging layer may be homogeneous comprising, forexample, a solid solution of two or more pigments. The imaging layer mayalso be heterogeneous comprising, for example, pigment particlesdispersed in a binder.

One technique for achieving low cohesive strength in the imaging layeris to employ relatively weak, low molecular weight materials therein.Thus, for example, in a single component homogeneous imaging layer, amonomeric compound or a low molecular weight polymer complexed with aLewis acid to impart a high level of photoresponse to the layer may beemployed. Similarly, when a homogeneous layer utilizing two or morecomponents in solid solution is selected to make up the imaging layer,either one or both of the components of the solid solution may be a lowmolecular weight material so that the layer has the desired low level ofcohesive strength. This approach may also be taken in connection withthe heterogeneous imaging layer. Although the binder material in theheterogeneous system may in itself be photosensitive it does notnecessarily have thisproperty. Materials may be selected for use as thisbinder material solely on the basis of physical properties withoutregard to their photosensitivity. This is also true of the two componenthomogeneous system in which photoinsensitive materials with the desiredphysical properties can be used. Any other technique for achieving lowcohesive strength in the imaging layer may also be employed. Forexample, suitable blends of incompatible materials such as a blend of apolysiloxane resin with a polyacrylic ester resin may be used either asthe binder layer in a heterogeneous system or in conjunction with ahomogeneous system in which the photoresponsive material may be eitherone of the incompatible components (complexed with a Lewis Acid) or aseparate and additional component of the layer. The thickness of theimaging layer whether homogeneous or heterogeneous ranges from about 0.2microns to about 25 microns generally about 1 micron to about 10 micronsand preferably about 5 microns.

The ratio of photosensitive pigment to binder, by weight, in theheterogeneous system may range from about 10 to l to about 1 to 10respectively, but it has generally been found that properties in therange of from about l to 4 to about 2 to 1 respectively produce the bestresults and, accordingly, this constitutes a preferred range.

The binder material in the heterogeneous imaging layer or the materialused in connection with the pigment materials in the homogeneous layer,where applicable, may comprise any suitable cohesively weak insulatingmaterial or materials which can be rendered cohesively weak. Typicalmaterials include: microcrystalline waxes such as: Sunoco 1290, Sunoco5825, Sunoco 985, all available from Sun Oil Co.; Paraflint RG,available from the Moore and Munger Company; paraffin waxes such as:Sunoco 5512, Sunoco 3425, available from Sun Oil Co.; Sohio Parowax,available from Standard Oil of Ohio; waxes made from hydrogenated oilssuch as: Capital City 1380 wax, available from Capitol City ProductsCo.. Columbus. Ohio; Caster Wax L-2790, available from Baker Caster OilCo.; Vitikote L-304, available from Duro Commodities; polyethylenes suchas: Eastman Epolene N-l l, Eastman Epolene C-l2, available from EastmanChemical Products Co.; Polyethylene DYJT, Polyethylene DYLT,Polyethylene DYDT, all available from Union Carbide, Corp.; Marlex TR822, Marlex 1478, available from Phillips Petroleum Co.; Epolene C-1 3,Epolene C-lO, available from Eastman Chemical Products Co.; PolyethyleneAC8, Polyethylene AC6l2, Polyethylene AC324, available from AlliedChemicals; modified styrenes such as: Piccotex 75, Piccotex 100,Piccotex 120, available from Pennsylvania Industrial Chemical;Vinylacetateethylene copolymers such as: Elvax Resin 210, Elvax Resin310, Elvax Resin 420, available from E. l. duPont de Nemours & Co.,Inc., Vistanex MH, Vistanex L-80, available from Enjay Chemical Co.;vinyl chloride-vinyl acetate copolymers such as: Vinylite VYLF,available from Union Carbide Corp.; styrene-vinyl toluene copolymers;polypropylenes; and mixtures thereof. The use of an insulating binder ispreferred because it allows the use of a larger range of electricallyphotosensitive pigments.

A mixture of microcrystalline wax and polyethylene is preferred becauseit is cohesively weak and an insulator.

Normally the imaging layer is coated onto the donor sheet or substratewhich had previously been coated with the solvent softenable layer. Forconvenience the combination of imaging layer, solvent softenable layerand donor substrate is referred to as the donor. In those instanceswherein the donor substrate is solvent softenable, the imaging layer andsubstrate are collectively referred to as the donor. When employing abinder in the imaging layer, the electrically photosensitive materialcan be fixed in the binder material by conventional means for blendingconventional solids as by ball milling. After blending the ingredientsof the imaging layer, the desired amount is coated onto the solventsoftenable layer of the donor sheet. in a particularly preferred form ofthe invention, an imaging layer comprising the electricallyphotosensitive material dispersed in a binder is coated onto atransparent, electrically insulating donor sheet.

The imaging layer may be supplied in any color desired either by takingadvantage of the natural color of the photosensitive material or bindermaterials in the imaging layer or by the use of additional dyes andpigments therein whether photoresponsive or not and, of course, variouscombinations of these photoresponsive and nonphotoresponsive colorantsmay be used in the imaging layer so as to produce the desired colorlayer.

The donor sheet and receiver sheet may comprise any suitableelectrically insulating or electrically conducting material. Insulatingmaterials are preferred since they allow the use of high strengthpolymeric materials. Typical insulating materials include polyethylene,polypropylene, polyethyleneterephthalate, cellulose acetate, paper,plastic coated paper, such as polyethylene coated paper, vinylchloride-vinylidene chloride copolymers and mixtures thereof. Mylar (apolyester formed by the condensation reaction between ethylene glycoland terephthalic acid available from E. I. duPont de Nemours & Co.,Inc.) is preferred because of its durability and excellent insulativeproperties. Not only does the use of this type of high strength polymerprovide a strong substrate for the positive and negative images formedon the donor substrate and receiver sheet but, in addition, it providesan electrical barrier between the electrodes and the imaging layer whichtends to inhibit electrical breakdown of the system while subjecting themanifold sandwich to an electrical field. The donor sheet and receiversheet may each be selected from different materials. Thus, a manifoldsandwich can be prepared by employing an insulating donor sheet while aconductive material is employed as a receiver sheet.

As stated above, according to the process of this invention, the imaginglayer is subjected to an electrical field. The electrical field can beapplied in many ways. Generally the sandwich is placed betweenelectrodes having different electrical potential. Also, an electricalcharge can be imposed upon one or both of the donor sheet and receiversheet before or after forming the sandwich by any one of several knownmethods for inducing a static electrical charge into a material. Staticcharges can be imposed by contacting the sheet or substrate with anelectrically charged electrode. Alternatively one or both sheets may becharged using corona discharge devices such as those described in U. S.Pat. No. 2,588,699 to Carlson, U. S. Pat. No. 2,777,957 to Walkup, U. S.Pat. No. 2,885,556 to Gundlach or by using conductive rollers asdescribed in U. S. Pat. No. 2,980,834 to Tregay et al., or by fractionalmeans as described in U. S. Pat. No. 2,297,691 to Carlson or othersuitable apparatus.

Thus, the electrical field can be provided by means known to the art forsubjecting an area to an electrical field. The electrodes employed maycomprise any suitable conductive material and may be flexible or rigid.Typical conductive materials include: metals such as aluminum, brass,steel, copper, nickel, zinc, etc., metallic coatings on plasticsubstrates, rubber rendered conductive by the inclusion of a suitablematerial therein, or paper rendered conductive by the inclusion of asuitable material therein or through conditioning in a humid atmosphereto insure the presence therein of sufficient water content to render thematerial conductive. Conductive rubber is preferred because of itsflexibility. In the process of this invention wherein the imaging layeris exposed to activating electromagnetic radiation while positionedbetween electrodes, one of the electrodes must be at least partiallytransparent. The transparent conductive electrode may be made of anysuitable conductive transparent material and may be flexible or rigid.Typical conductive transparent materials include cellophane,conductively coated glass, such as tin or indium oxide coated glass,aluminum coated glass, or similar coatings on plastic substrates. NESA,a tin oxide coated glass available from Pittsburgh Plate Glass Co., ispreferred because it is a good conductor and is highly transparent andis readily available. In the process of this invention wherein the donorand/or receiver is composed of conductive material each may also beemployed as the electrodes by which the imaging layer is subjected to anelectrical field. That is either when employed as an electrode one orboth of the donor sheet and receiver sheet may serve a dual function inthe process of this invention.

The strength of the electrical field applied across the manifoldsandwich depends on the structure of the manifold sandwich and thematerials used. For example, if highly insulating receiver and donorsubstrate materials are used, a much higher field may be applied than ifrelatively conductive donor and receiver sheets are used. The fieldstrength required may be, however, easily determined. If too large apotential is applied, electrical breakdown of the manifold sandwich willoccur allowing arcing between the electrodes. If too little potential isapplied, the imaging layer will not fracture in imagewise configuration.By way of example, if a 3 mil Mylar receiver sheet and a 2 mil Mylardonor sheet are used, potentials as high as 20,000 volts may be appliedbetween the electrodes. The preferred field strengths across themanifold sandwich are, however, in the range of from about 1,000 voltsper mil to about 7,000 volts per mil of electrically insulatingmaterial. Since relatively high potentials are utilized, it is desirableto insert a resistor in the circuit to limit the flow of current.Resistors on the order of from about I megohm to about 20,000 megohmsare conventionally used.

Initially, whether the positive image is formed on the donor sheet orthe receiver sheet depends on the imaging layer materials used and/orthe polarity of the applied field. It has been found in general,however, if the donor side electrode is held at a positive potential inrespect to the receiver side electrode, that the positive image isformed on the donor sheet and a negative image is formed on thereceiving sheet. That is, the illuminated portions of the imaging layeradhere to the receiver sheet and the non-illuminated areas of theimaging layer adhere to the donor sheet. It has also been found, ingeneral, that when the imaging layer is coated onto a donor sheet, thebest quality images are produced by exposing through the donor sheet.

A visible light source, an ultraviolet light source or any othersuitable source of electromagnetic radiation may be used to expose theimaging layer of this invention. The electrically photosensitivematerial is chosen so as to be responsive to the wavelength of theelectromagnetic radiation used. It is to be noted that differentelectrically photosensitive materials have different spectral responsesand that the spectral response of many electrically photosensitivematerials may be modified by dye sensitization so as to either increaseor narrow the spectral response of a material to a peak or to broaden itto make it more panchromatic in its response.

The imaging layer can be exposed to electromagnetic radiation at anypoint in the process prior to field modification including prior toforming the manifold sandwich. Alternatively, the process of thisinvention can include the steps (I) exposing the imaging layer toactinic electromagnetic radiation (2) placing the receiver on theimaging layer forming a manifold sandwich (3) subjecting the sandwich toan electrical field (4) modifying the field and (5) separating thesandwich. For example, one embodiment of the process of this inventionare the steps of l) imposing an electrical charge on the donor as bycorona discharge (2) exposing the imaging layer to electromagneticradiation to which it is sensitive (3) forming the manifold sandwich ofthe donor (4) modifying the field and (5) separating the sandwich.

In addition, the activation step can be included at any point in theprocess prior to the separation of the sandwich. The sequence of stepsof the process of this invention including the optional activation stepcan be further varied by those skilled in the art without departing fromthe scope of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of this invention willbecome apparent upon consideration of the detailed disclosure of theinvention, especially when taken in conjunction with the accompanyingdrawings wherein:

FIG. 1 is a side sectional view of a photosensitive imaging member foruse in this invention;

FIG. 2 is a side sectional view diagrammatically illustrating theactivation step and the formation of the manifold sandwich;

FIG. 3 is a side sectional view diagrammatically illustrating the finaltwo process steps of this invention, including imagewise exposure andsandwich separation while under an electric field;

FIG. 4 is a process flow diagram of the method steps of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1,imaging layer 6 comprising photosensitive particles 7 dispersed inbinder 8 is deposited on insulating donor sheet 5. Donor sheet has beenpreviously prepared by having coated thereon a solvent softenable layer4, which adheres tightly to donor sheet 5 and is preferably transparentto electromagnetic radiation to which imaging layer 6 is sensitive. Theimage receiving portion of the manifold imaging member comprisesinsulating receiver sheet 9. Although shown in the attached drawing asinsulating, receiver sheet 9 may be either electrically conductive orinsulating. In addition, either or both sheets 5 and 9 may betransparent so as to permit exposure of imaging layer 6. The embodimentof the invention shown in FIG 1 is preferred because it allows for theuse of high strength insulating polymeric materials as donor sheet 5 andreceiver sheet 9.

Referring now to FIG. 2 which diagrammatically illustrates theactivation step and the formation of the manifold imaging member orsandwich, FIG. 2 shows the activator fluid 23 being sprayed onto theimaging layer 12 of the manifold imaging member from container 24.Alternatively, the activator may be applied by any suitable techniquessuch as with a brush, with a smooth or rough surface roller, by flowcoating or the like. The activator serves to swell or otherwise weakenand thereby lower the cohesive strength of imaging layer 12. Inaddition, the activator after permeating imaging layer 12 softens orpartially dissolves or swells the solvent softenable layer 11. Electrodel7 and receiver sheet 16 are then lowered onto imaging layer 12 andoptional roller 26 is rolled across the surface of electrode 17 toremove any excess activator fluid which may be present. The use ofroller 26 may be omitted and in those instances wherein the solventsoftenable layer 11 is soluble in the activator employed. Electrodes 17and 18 may be separate members or they may be integralparts of the donorsheet and receiver sheet. Thus, transparent conductive cellophane may beemployed both as an electrode and as a donor or receiver sheet in theimaging member of this invention.

Referring now to FIG. 3 the imaging member is charged by connectingelectrodes 17 and 18 to potential source 28 and resistor 30. The imagingmember is then exposed to electromagnetic radiation 29 in imageconfiguration. Receiver sheet 16 and donor sheet 19 are then separated.Upon separation imaging layer 12 fractures along the edges of exposedareas and at the surface where it adhered to substrate solventsoftenable layer on donor sheet 19. Accordingly, when separation iscompleted exposed portions of imaging layer 12 are retained on one ofthe layer 16 and 19 while unexposed portions are retained on the otherlayer. Although FIG. 3 shows a positive image being formed on donorsheet, it is possible to form a negative image on the donor sheet.Alternatively, solvent softenable layer 15 may be coated on the receiversheet 16 and form subbing layer under the portions of the imaging layer12 which is transferred to receiver sheet 16. Thus, the object of 1 thisinvention can be accomplished by coating either the receiver sheet ordonor sheet with a solvent softenable layer.

After sandwich separation as shown in FIG. 3, the image is desirablyfixed to the substrate by mild heating which evaporates the activatorleaving a well fixed, smooth, scratch resistant image.

Activation of the imaging layer may take place by employing yet anotherlayer in the imaging member. There can be employed a thermosolvent whichupon heating becomes a liquid and acts as an activator to the imaginglayer and the solvent softenable layer. Such thermosolvents aredescribed in copending application Ser. No. 675,989 filed Oct. 17, 1967,now abandoned, which is incorporated herein by reference.

The following examples further specifically illustrate the presentinvention. The examples below are intended to illustrate variouspreferred embodiments of the improved imaging de cri above.

EXAMPLES I-IX A donor sheet consisting of 2 mil polyester film soldunder the trade name of Mylar by the E. I. duPont de Nemours & Co., Inc.is first coated with a layer of solvent softenable material. The solventsoftenable material is prepared by slurrying in toluene 10 percent byweight of the material. The slurry is then hand coated with a No. l2wire-wound drawdown rod onto the Mylar. The coating is dried in an ovenat a temperature of about 70 to about C. for periods of from five tofifteen minutes. The coated Mylar is then overcoated with an imaginglayer comprising an electrically photosensitive material dispersed in abinder. The binder material is prepared by dissolving in hot petroleumether eight parts of polyethylene AC-8 available from Allied ChemicalCompany, one part of Vistanex L-8O and one part of Vistanex MI-I both ofwhich are vinyl acetate-ethylene copolymers available from the EnJayChemical Company and mil of petroleum ether (90-120 C.). The hotsolution is poured into 1 liter of isopropyalcohol with agitation andleft standing overnight. The suspension is then filtered, reslurried in1 liter of isopropyl-alcohol, filtered again to a damp cake containingabout 20 percent solids. A suspension of an electrically photosensitivematerial is prepared by first purifying a commercial, metal-freephthalocyanine. The commercial material is first purified by acetoneextraction to remove organic impurities. Since this extraction stepyields the less sensitive beta crystalline form, the alpha form isobtained by dissolving I00 parts of the beta form in 600 cc. of sulfuricacid, precipitating by pouring the solution to about 3 liters of icewater and washing with water to neutrality. The thus purifiedphthalocyanine is then salt milled for six days and desalted byslurrying in distilled water, vacuum filtered, water washed and methanolwashed until the initial filtrate is clear. After vacuum drying toremove residual methanol, the X-form phthalocyanine is dispersed in abinder solution prepared as described above. About two parts of theabove described phthalocyanine is slurried in 100 mil of isopropanyl.About 10 mil of this dispersion is mixed with about two parts of thebinder material and additional 5 mil of isopropanol. This paste mixtureis then coated on the donor prepared as described above using a No. 12wirewound drawdown rod, and the donor is oven dried at 75 C. for 5minutes. The donor is taped to a transparent electrode with the imaginglayer side up. The transparent electrode is a tin oxide-coated glassavailable from the Pittsburgh Plate Glass Company under the trade nameNESA. The imaging layer is covered with a sheet of aluminized styrenewet on the non-aluminized side with an activator which in this case is akerosene fraction sold under the trade name of Sohio Odorless Solvent3440 available from The Standard Oil Company. The imaging membercomprising the aluminized styrene, the imaging layer and the coateddonor sheet is rolled fiat with a soft rubber roller and an electricpotential is applied between the aluminized side of the styrene sheetand the NESA glass electrode from a 10KV direct current power supplywith the NESA glass made the positive pole. The imaging layer is exposedto an imagewise pattern of light from a white incandescent light sourcefor a period of about two seconds through the NESA glass and thetransparent donor sheet. With the voltage still applied, the receiversheet is separated from the donor sheet. The image on the donor sheet isheated by hot air for a few seconds providing a clear, smooth surfacethat is well fixed. In Table I below there is listed solvent softenablematerials which are employed in the above described example. Theprocedure for each Example I-IX is repeated except for the solventsoftenable layer which is listed in Table I for each example. There isalso shown in Table I the solubility of the solvent softenable materialin the Sohio Odorless Solvent employed as the activator in the manifoldimaging process TABLE I Solvent Soitonable Layer Example Type PhysicalProperty Trade Name Manufacturer Solubility I Ethylene-vinyl acetatecopolymer. Ring atndgbalsoitoning Nevex 100 Neville Chem. Co Soluble,

pom II Polystyrene Ring and ball point 75 C Piccolastlo A75 PennsylvaniaIndustrial Do.

mol. wt. 400. Chem. Corp. III Alphamethyl-styrene- Ring and ballsoftening Piccotex 120 Same Partially soluble.

vinyltoluene copolymer. point-120 C. IV Polymerized rosin and glycerinRing and ball softening VBR 4000 Nelio Corp Soluble.

reaction product. point--105 C.110 C. V Alphamethylstyrene-styrene Nalgesoftening point 55 C. 4 D0.

copolymer (mol. ratio 67/33). 70 C. intrinsic vise. .029 in toluene atC. \I Vinyltoluene n-butyl Melt index17 Partially soluble.

methacrylate copolymer (60/40 wt. percent). \II Vinyltoluene n-butylMelt index-61. D0.

methacrylate copolymer (62/37 wt. percent). 33}% vinylidene-acrylicterpolymer.

Melting point-100 C (Staudlger) Intrinsic Vise.

(dl/g) 2.04-2.57.

Alphaprene A100. Reichhold Chem. Inc... Soluble.

Piocotex 75 Pennsylvania Industrial Insoluble.

Chem. Corp. Piceotex 120 Same Partially soluble.

Vistanex MM L80... EnJay Chem. Company Insoluble.

EXAMPLE X Example Ill is repeated except that an oil soluble red dye,Calco Oil Red N-l700 available from American Cyanamid Company isincorporated into the Piccotex 120 subcoating on the donor sheet. Theresulting image residing on the donor sheet now has a red background.The image is fixed to the donor sheet by heating slightly to evaporatethe Sohio Odorless Solvent. The image is projected by means of anoverhead projector giving unusual color effects due to the red dye inthe subcoating.

Images produced by the above examples can be employed in projectionslides for use in the various types of projectors. By employing variousdyes in the solvent softenable layer, unusual color effects may beobtained when the image is projected. Particularly, effects can beobtained, for example, by employing a purple colored imaging layer on atransparent red solvent softenable layer or a green imaging layer on atransparent yellow solvent softenable layer. It is to be noted thatimages produced in accordance with this invention can be employed afterfixin directly as a projection image without urther treatment. reviousy, images produced in accordance with the prior art in manifold imagingprocess required polishing or buffing in order to obtain true colorprojection images.

Although specific components in proportion have been stated in the abovedescription of the preferred embodiment of the invention, other typicalmaterials as listed above if suitable may be used with similar results.In addition, other materials may be employed to synergize, enhance orotherwise modify the properties of the solvent softenable layer. Forexample, various dyes, particles made up of two or more layers, blendsof materials, complexes and electrical sensitizers such as Lewis acidmay be added to the solvent softenable layer.

Other modifications and ramifications of the present invention willoccur to those skilled in the art upon a reading of the presentdisclosure. These are intended to be included within the scope of thisinvention.

What is claimed is:

1. An imaging method which comprises the steps of b. activating saidimaging layer with an activator, said activator comprising anelectrically resistive solvent capable of at least softening saidfixative layer, whereby said imaging layer mixes with said first layer,

subjecting said imaging layer to an electric field, exposure toelectromagnetic radiation actinic to said material and a receiver sheetoverlying said imaging layer,

. exposing said imaging layer to a pattern of electromagnetic radiationto which said layer is sensitive and,

. while under said field separating said donor and receiver sheetwhereby said imaging layer fractures in imagewise configuration with theexposed portion residing on one of the donor and receiver sheets and theunexposed portion residing on the other of said sheets.

2. The method of claim 1 further including the step of fixing by meansof heat at least one of said exposed and unexposed portions of saidimaging layer.

3. The method of claim 1 wherein the solvent softenable material is athermoplastic material.

4. The method of claim 1 wherein the electrically photosensitivematerial is an organic material.

5. The method of claim 4 wherein the organic material is phthalocyanine.

6. The method of claim 1 wherein the fixative layer contains a dyematerial.

7. The method of claim 1 wherein the fixative layer comprises at leasttwo materials at least one of which is at least softenable in saidactivator and one of which is insoluble in said activator.

8. The method of claim 1 wherein the fixative layer is from about 1micron to about 5 microns in thickness.

9. The method of claim 1 wherein the donor sheet and the solventsoftenable layer are transparent.

10. The method of claim 1 wherein the fixative layer comprises amodified polystyrene.

prises a styrene-vinyl toluene copolymer.

lljThe method ofclaim 1 wherein the fixative layer com- I g UNITEDSTATES PATENT OFFICE CERTIHCATE CF CGRREC'MGN Patent No. 3, 653, 889Dated 4/4/7 Invent0r(8) Ray H. Luebbe Jra & John F. Br' 'ne It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

r column 1, line 34, "t0" should read ---to-- "'1 Column 4, line 9,delete --phenanthrenylazo) phloroglucinol,--;

Column 4, line 39, "carboxyphphenyl" should read --carboxyp'henyl-;Column 4, line 43, "debenzoylamine" should read -dibenzoylamine--;

Column 4, line 52, "bephenyl" should read -biphenyl--; Column 4, line68, "tetanium" should read -titanium- Column 5, line 6, "nuphthylidene"should read -naphthylidene--;

Column 5, line 6, "2-phenyl4 diphenylidene-pxayoline" should read2-phenyl-4-diphenylidene oxazoline- Column 5, line 49, "caldium" shouldread --cadmium-f Column 5, line 54, "sulphonoc" should read -sulphonic--Column 6, line 58, "phthalocyanium" should read --phthalocyanine--Column 7, line 6, "tetraphyridylphthalocyanine" should read tyridylphthalocyanine-- Column 9, line 30, "fractional" should read-frictional-- Column 12, line 21, "mil" should read --ml.'-;

Column line ispropyalcohol" should read -isoprop'y"-J alcohol--;

fg ggy UNITED STATES PATENT ormcs QETEFICATE Gi 430 Patent No 3 653, 889Dated 4/4 72 Inventor( Ray H. Jr. 84 F. Bryne 2 It is certified thaterror appears in the above-identified patentand that said Letters Patentare hereby corrected as shown below:

Column 12, line 42, "mil" should read --ml., both Occurrences;

Cplumn 12, line 44, "mil" should read ml,--

Claim 1, line 1, insert after "of" (a) providing a donor sheet and areceiver sheet and sandwiched therebetween a fixitive layer comprisingsolvent softenable material and an 7 imaging layer comprisingelectrically photosensitive material) said material being structurallyfractur-able in response to the combined effects of an applied electricfield and exposure to electromagnetic radiation to said material,-

Claim 1, line 1 of (c) delete "exposure to electromagnetic radiationactinic to said material and a receiver sheet overlying said imaginglayer" Claim 9, line 2, delete "solvent softenable" and insert in itsplace -fixitive-. I

and sealed this 1st day of May 1973.

JR, ROBERT GOTTSCHAIK Commissioner of Patents

2. The method of claim 1 further including the step of fixing by meansof heat at least one of said exposed and unexposed portions of saidimaging layer.
 3. The method of claim 1 wherein the solvent softenablematerial is a thermoplastic material.
 4. The method of claim 1 whereinthe electrically photosensitive material is an organic material.
 5. Themethod of claim 4 wherein the organic material is phthalocyanine.
 6. Themethod of claim 1 wherein the fixative layer contains a dye material. 7.The method of claim 1 wherein the fixative layer comprises at least twomaterials at least one of which is at least softenable in said activatorand one of which is insoluble in said activator.
 8. The method of claim1 wherein the fixative layer is from about 1 micron to about 5 micronsin thickness.
 9. The method of claim 1 wherein the donor sheet and thesolvent softenable layer are transparent.
 10. The method of claim 1wherein the fixative layer comprises a modified polystyrene.
 11. Themethod of claim 1 wherein the fixative layer comprises a styrene-vinyltoluene copolymer.